1. Field of the Invention
The present invention relates to a single speed, chainless drive transmission for a pedal-propelled vehicle such as a bicycle.
2. Description of the Prior Art
The conventional single speed bicycle drive is characterized by a pedal and crank assembly which rotates a pedal sprocket to drive a chain for rotating a rear sprocket coupled to the wheel hub. The chain requires periodic cleaning for efficient operation and must be removed to change the rear tire. Cleaning is particularly necessary in dusty areas to prevent hard pedaling and premature chain failure.
The chainless drive systems of the prior art are either impractical or excessively complex or costly to manufacture and maintain. U.S. Pat. No. 1,798,384 entitled "Cycle Driving Apparatus", issued Mar. 31, 1931 to G. A. Roberds is typical of one form of chainless drive. The gearing arrangement is chainless and compact if the gear ratio is 1.5 to 1 but must be limited to about 1.7 to 1 or the components become impracticably large. Also, with Roberd's design, there appears no way to change the tire without dismantling the transmission.